Example embodiments relate to semiconductor devices and methods of forming semiconductor devices. As an integration degree of semiconductor devices such as Dynamic Random Access Memory (DRAM) devices has increased, a contact area of a contact may decrease and may thereby increase contact resistance. In addition, as the size of a Metal Oxide Semiconductor (MOS) transistor decreases, defects such as punch through, short channel effect, body portion leakage current, and gate-induced drain-leakage (GIDL), etc. may be generated.